The anticancer drug paclitaxel (taxol) derived from the pacific yew has many effects on mitosis. one of its most powerful effects is that it prevents disassembly of the mitotic spindle which prevents spindle fibers from shortening. which phase of mitosis would this directly affect? why would this stop cell division overall and lead to cell death?

The anticancer drug paclitaxel has effects like it prevents disassembly of the mitotic spindle which prevents spindle fibers from shortening.

During anaphase of mitosis, the cell spindle fibers shorten and paclitaxel act directly in this (anaphase) same phase and prevent metaphase to achieve that is required for the cell growth and development.

This leads to the cell growth prevention through mitosis and hence lead to the death of the cell by apoptosis.